WorldWide Tattoo Supply CONVENTIONAL SPRINGS will fit onto all conventional tattoo machines. Our springs are sold flat, and must be bent by the purchasers to their preference. All our springs are made of high carbon spring steel or blue tempered high carbon spring steel. Polished Conventional Springs Available in 11 Thickness: 0.013", 0.014", 0.015", 0.016", 0.017", 0.018", 0.019", 0.020", 0.021", 0.022", 0.023". Back Spring: 3.4cm (L) x 1.3cm (W)